A Laboratory Plate/Screen-Type Electrostatic Separator for Granular Mixtures: Design,Engineering, and Application

The plate/screen-type electrostatic separator presented in this article provides a user-friendly environment for the experimental modeling of existing industrial units and facilitates investigations aiming at identifying new possibilities for using electric field forces for processing mixed granular solids. This multifunctional unit can be equipped with two different active electrodes, which can be energized from one or two independent high-voltage supplies, and the operator has the choice between two types of grounded electrodes: plate and plate/screen. The experiments carried out on a 50% quartz-50% magnetite mixture demonstrate that the efficiency of the separation can be increased by using a grounded plate/screen electrode and two high-voltage electrodes, energized from different supplies.     

A Laboratory Plate/Screen-Type Electrostatic Separator for Granular Mixtures: Design, Engineering, and Application

The plate/screen-type electrostatic separator presented in this article provides a user-friendly environment for the experimental modeling of existing industrial units and facilitates investigations aiming at identifying new possibilities for using electric field forces for processing mixed granular solids. This multifunctional unit can be equipped with two different active electrodes, which can be energized from one or two independent high-voltage supplies, and the operator has the choice between two types of grounded electrodes: plate and plate/screen. The experiments carried out on a 50% quartz-50% magnetite mixture demonstrate that the efficiency of the separation can be increased by using a grounded plate/screen electrode and two high-voltage electrodes, energized from different supplies.     

柴油车微粒捕集器过滤材料研究进展

论述了几种类型过滤材料的特性及在柴油车微粒捕集器中的应用状况，分析了过滤材料面临的几个主要问题，并展望了其应用前景。     

Experimental Modeling of the Electrostatic Separation of Granular Materials

This article aims at demonstrating the interest the design of experiment methodology might present for modeling and optimization of a typical electrostatic separation process. A classical 2³ full-factorial design followed by a composite design were employed for carrying out experiments on the selective sorting of conductive and nonconductive particles contained in a granular mixture. The study was performed on a roll-type corona-electrostatic separator, with samples prepared from genuine electric cable wastes, composed of 5% copper and 95% PVC. The response function was the mass of the middling fraction collected after separation, the factors under investigation being the high-voltage level, the speed of the rotating roll electrode, and the angular position of the splitter between the copper and middling compartments of the collector. By using commercial design of experiments software, it was possible to estimate the effects of these factors and then derive the model of the process as a quadratic polynomial function. This model served at predicting the optimal set point of the process. The results reported support design of experiments methodology as an efficient tool for the optimization of industrial electrostatic separation processes.     

静电喷涂中荷电油液的雾化研究

对油液在高压静电场中的荷电过程及其雾化机理进行了理论分析和试验研究，得到了雾滴粒径与电极电压、涂油刀梁刃口曲率半径和间隙的关系，并根据实验结果对液滴分裂的荷电量公式进行了修正，为静电喷涂中的各参数选择和工艺控制提供了依据。     

On Effective Energy Reflectance of Particulate Materials

This paper investigates the effective energy reflectance of materials comprised of a continuous matrix embedded with fine-scale particles of different electric permittivity and magnetic permeability. The specific objective is to determine under what conditions will increasing the particulate volume fraction initially increase (or decrease) the overall reflectance from a pure-matrix base state and, with further increase in volume fraction, reverse the trend, i.e. decrease (or increase) the effective reflectance. The importance of this condition is that it indicates when the correlation of a specific level of reflectance to a specific volume fraction of particles may not be unique, even when the properties of the particles and matrix are fixed.     

Measurement and Control of Triboelectrically Charged Silica and Glassy Carbon Particles

In this study, a particle trajectory analysis and charging measurements of triboelectrically charged silica and glassy carbon particles were conducted to investigate the effects of charging gas velocity and particle size on triboelectrical charging characteristics. A particle motion analysis system (PMAS) was used to measure charged particle motion information in the separation chamber with an applied uniform electric field, and the particle charging amount was calculated from the particle size and the electrostatic mobility was determined by the PMAS. The test system consisted of a particle generator, a spiral-type tribocharger made of a copper tube, and a particle motion analysis system to measure the particle size and velocity. The experiments were conducted with test particles of silica and glassy carbon and the average charging gas velocities of 6, 10, 15, 20 m/s to analyze the effect on particle charging. As a result, the silica and glassy carbon particles acquired negative and positive charges, respectively, due to the differences in the work functions, and the charging gas velocity effect on particle charge was approximately linear with an increasing velocity yielding a higher average particle charge and wider distribution.     

Measurement and Control of Triboelectrically Charged Silica and Glassy Carbon Particles

In this study, a particle trajectory analysis and charging measurements of triboelectrically charged silica and glassy carbon particles were conducted to investigate the effects of charging gas velocity and particle size on triboelectrical charging characteristics. A particle motion analysis system (PMAS) was used to measure charged particle motion information in the separation chamber with an applied uniform electric field, and the particle charging amount was calculated from the particle size and the electrostatic mobility was determined by the PMAS. The test system consisted of a particle generator, a spiral-type tribocharger made of a copper tube, and a particle motion analysis system to measure the particle size and velocity. The experiments were conducted with test particles of silica and glassy carbon and the average charging gas velocities of 6, 10, 15, 20 m/s to analyze the effect on particle charging. As a result, the silica and glassy carbon particles acquired negative and positive charges, respectively, due to the differences in the work functions, and the charging gas velocity effect on particle charge was approximately linear with an increasing velocity yielding a higher average particle charge and wider distribution.     

Characteristics of Air-Side Particulate Fouling Materials in Finned-Tube Heat Exchangers of Air Conditioners

ABSTRACT

Heat exchangers are used widely in residential, commercial, and industrial HVAC applications. Air-side particulate fouling in the heat exchangers of HVAC applications degrades the performance of cooling capacity, pressure drop across a heat exchanger, and indoor air quality. Indoor and outdoor air contaminants foul heat exchangers. The purpose of this study is to investigate the characteristics of the air-side particulate fouling materials in finned-tube heat exchangers of air conditioners. Air conditioners being used in the field such as inns, restaurants, and offices are collected in chronological order of use. The fouling materials attached on the evaporator heat exchangers consist of particulates and fibers. The particulates mainly originate from indoor dusts and the fibers are separated from clothes, bedclothes, papers, fur of pets, and so on. Typical fouling materials on the heat exchangers include fibers and dusts ranging from 6.6 to 20.9 μm in aerodynamic mean diameter.     

Characteristics of Air-Side Particulate Fouling Materials in Finned-Tube Heat Exchangers of Air Conditioners

Heat exchangers are used widely in residential, commercial, and industrial HVAC applications. Air-side particulate fouling in the heat exchangers of HVAC applications degrades the performance of cooling capacity, pressure drop across a heat exchanger, and indoor air quality. Indoor and outdoor air contaminants foul heat exchangers. The purpose of this study is to investigate the characteristics of the air-side particulate fouling materials in finned-tube heat exchangers of air conditioners. Air conditioners being used in the field such as inns, restaurants, and offices are collected in chronological order of use. The fouling materials attached on the evaporator heat exchangers consist of particulates and fibers. The particulates mainly originate from indoor dusts and the fibers are separated from clothes, bedclothes, papers, fur of pets, and so on. Typical fouling materials on the heat exchangers include fibers and dusts ranging from 6.6 to 20.9 μm in aerodynamic mean diameter.     

Electrostatic Separation of Peeling and Gluten from Finely Ground Wheat Grains

Sieving and air classification are not efficient enough for the extraction of the high-nutritional-value constituents of wheat. The aim of this article is to validate a simple electrostatic separation method of peeling and gluten, which are two such nutriments contained in finely ground wheat grains. The electrostatic separator is composed of metallic grounded belt conveyer and a rotating roll electrode connected to a high voltage supply. The electrostatic behavior of peeling and gluten powders was characterized using surface potential decay and direct charge measurements. These first set of experiments pointed out the conductive behavior of these powders: in contact with a grounded electrode, they lose their charge in less than 10 s. In a second set of experiments, mixtures of 50% peeling and 50% gluten powders were processed by electrostatic separation. Experimental design methodology was used to model the outcome of the separation process as function of two control variables: the high-voltage applied to the roll electrode and the speed of the belt conveyor electrode. In this way, it was possible to determine the optimal operational conditions for the recovery of high-purity peeling and gluten fractions.     

Triboelectric Separation of Three-Component Plastic Mixture

The results of an experimental study on the triboelectric separation of one type of plastic from a three-component plastic mixture are presented. A triboelectric separator, which consists of a vibratory conveyor equipped with two electrodes, was used. The separation method makes it possible to avoid the adhesion of oppositely charged particles. Separation tests were performed on two kinds of mixtures. The effect of operating parameters such as electric field strength, polarity of applied voltage, and triboelectric charging time on the separation efficiency was examined. In the case of the separation of a mixture of 50% polyvinyl chloride (PVC), 50% polyethylene terephthalate (PET), and 50% polyethylene (PE), the purity of the extracted PVC was larger than 99% for a recovery rate of 94.9%. In the case of the separation of a mixture of 50% acrylonitrile butadiene styrene (ABS), 50% polypropylene (PP), and 50% polystyrene (PS), the purity of the extracted ABS was larger than 99% for a recovery rate of 89.4%.     

Vibratory Separation of Plastic Mixtures Using Triboelectric Charging

This article presents the results of experimental and analytical studies of the performance of a novel vibratory separator of plastic mixtures for recycling. The separator unit consists of a vibratory conveyor equipped with two plate electrodes. The principle behind the separation technique is based on the difference in Coulomb force acting on the plastic particles after triboelectric charging. The separation of a mixture of 50% polyvinylchloride (PVC) and 50% polyethylene terephthalate (PET) using this method was studied. An analytical model describing the relative distribution of the two types of plastic particles in the collection trays was developed. The effect of triboelectric charging time and electric-field strength on the separation efficiency was investigated.     

Vibratory Separation of Plastic Mixtures Using Triboelectric Charging

This article presents the results of experimental and analytical studies of the performance of a novel vibratory separator of plastic mixtures for recycling. The separator unit consists of a vibratory conveyor equipped with two plate electrodes. The principle behind the separation technique is based on the difference in Coulomb force acting on the plastic particles after triboelectric charging. The separation of a mixture of 50% polyvinylchloride (PVC) and 50% polyethylene terephthalate (PET) using this method was studied. An analytical model describing the relative distribution of the two types of plastic particles in the collection trays was developed. The effect of triboelectric charging time and electric-field strength on the separation efficiency was investigated.     

A sensor for estimating the buildup of static electricity on special clothes under practical conditions

The problems of monitoring the buildup of static charge on clothes under practical conditions are considered. A measuring instruments is proposed which enables the electrostatic field strength to be estimated in the region of the surface of a textile material and which indicates when its maximum permissible value is being approached. Translated from Izmeritel’naya Tekhnika, No. 4, pp. 45–46, April, 2009.     

Fluidized Bed Device for Plastic Granules Triboelectrification

The study of the triboelectrification process is the key factor to the successful industrial application of electrostatic separation in the field of plastics recycling. Therefore, the aim of the present work is to evaluate an original device for the laboratory study of this process. The original design of the fluidized bed type triboelectrification device has the following distinctive features: (i) transparent walls to observe the fluidization process and the particles moving in the triboelectrification module; (ii) air distributors with different mesh apertures correlated with granule size; (iii) quick replacement of the triboelectrification Plexiglas chamber with other metallic (aluminium, copper) or nonmetallic chambers (polyvinyl chloride—PVC, polyethylene—PE, and polyethylene terephthalate—PET); (iv) possibility of independent operation, for granule charge measurement or integrated operation, for the electrostatic separation experiments using a free-fall electrostatic separator. The results of charge measurement experiments pointed out the different triboelectric behaviour of two types of granules (polystyrene and low-density polyethylene) in contact with the walls of the device. The electrostatic separation experiments carried out on a binary mixture of mm-size polystyrene/polyethylene granules confirmed the effectiveness of the triboelectrification device.     

Fluidized Bed Device for Plastic Granules Triboelectrification

The study of the triboelectrification process is the key factor to the successful industrial application of electrostatic separation in the field of plastics recycling. Therefore, the aim of the present work is to evaluate an original device for the laboratory study of this process. The original design of the fluidized bed type triboelectrification device has the following distinctive features: (i) transparent walls to observe the fluidization process and the particles moving in the triboelectrification module; (ii) air distributors with different mesh apertures correlated with granule size; (iii) quick replacement of the triboelectrification Plexiglas chamber with other metallic (aluminium, copper) or nonmetallic chambers (polyvinyl chloride—PVC, polyethylene—PE, and polyethylene terephthalate—PET); (iv) possibility of independent operation, for granule charge measurement or integrated operation, for the electrostatic separation experiments using a free-fall electrostatic separator. The results of charge measurement experiments pointed out the different triboelectric behaviour of two types of granules (polystyrene and low-density polyethylene) in contact with the walls of the device. The electrostatic separation experiments carried out on a binary mixture of mm-size polystyrene/polyethylene granules confirmed the effectiveness of the triboelectrification device.     

2D Layered Materials for Fast-Charging Lithium-Ion Battery Anodes

The development of electric vehicles has received worldwide attention in the background of reducing carbon emissions, wherein lithium-ion batteries (LIBs) become the primary energy supply systems. However, commercial graphite-based anodes in LIBs currently confront significant difficulty in enduring ultrahigh power input due to the slow Li⁺ transport rate and the low intercalation potential. This will, in turn, cause dramatic capacity decay and lithium plating. The 2D layered materials (2DLMs) recently emerge as new fast-charging anodes and hold huge promise for resolving the problems owing to the synergistic effect of a lower Li⁺ diffusion barrier, a proper Li⁺ intercalation potential, and a higher theoretical specific capacity with using them. In this review, the background and fundamentals of fast-charging for LIBs are first introduced. Then the research progress recently made for 2DLMs used for fast-charging anodes are elaborated and discussed. Some emerging research directions in this field with a short outlook on future studies are further discussed.